1. Field of the Invention
The present invention relates to a method of forming a weld bead of metal, and more particularly a method of forming a weld bead of pure copper on a ferroalloy base material.
2. Description of the Prior Art
It is already known to provide a coating membrane of copper or a copper alloy on the surface of a cast iron material and thereafter to melt the coating membrane by a high density energy source so as thereby to turn the coating membrane into a weld bead, as disclosed, for example, in Japanese Patent Laid-open Publication 62-101392. According to this method it is possible to obtain a weld bead having no cracks or blow holes.
However, when this method is used for copper in such a manner that a powder of pure copper is laid on the surface of a cast iron material and the powder is melted by a high density energy source in order to form a weld bead of pure copper on the cast iron material, the graphite in the cast iron diffuses into the coating membrane, and therefore a weld bead having a high copper content can not be formed on the base material.
As a result of various experimental research efforts for forming a weld bead of pure copper on a cast iron material in view of the above-mentioned problem, the inventors of the present application have succeeded in forming a weld bead having a high copper content on a ferroalloy base material by mixing a powder of pure copper with a powder of an auxiliary metal which satisfies certain particular conditions.